In the related art, for example, piezoelectric power generators described in Patent Literatures 1, 2, and 3 are known as piezoelectric power generators that extract electrical power by converting kinetic energy inputted from the outside, into electrical energy using a piezoelectric element, and supply the electrical power to an electrical storage device or the like.
In general, a piezoelectric substrate is supported in a cantilevered state such that one end thereof is fixed and another end thereof is a free end to which a weight is provided. In Patent Literature 1, a piezoelectric substrate is thinned toward a free end thereof, and in Patent Literature 2, a piezoelectric substrate is narrowed in width toward a free end thereof. In addition, in Patent Literature 3 describes a piezoelectric device that is composed of a continuous piezoelectric element that includes a plurality of straight portions arranged and stacked parallel to each other and is folded in zigzag.
Meanwhile, in a cantilever type power generator as described in Patent Literatures 1 and 2, in order to increase an amount of power generation, a cantilever has to be long in length and a vibration space also has to be large. Thus, the power generator is inevitably made large in size. In the piezoelectric device described in Patent Literature 3, size reduction is possible. However, stress tends to concentrate on a fixed end of a stacked piezoelectric element, and thus there is a problem that the fixed end is likely to break. In addition, effective measures have not necessarily been taken to improve power generation efficiency.    Patent Literature 1: Japanese Unexamined Patent Application Publication No. 10-56784    Patent Literature 2: Japanese Unexamined Patent Application Publication No. 10-174462    Patent Literature 3: Japanese Patent No. 4220901